optimized building automation and control for the ...

POLLACK PERIODICA An International Journal for Engineering and Information Sciences DOI: 10.1556/Pollack.10.2015.1.7 Vol. 10, No. 1, pp. 71–82 (2015) www.akademiai.com

OPTIMIZED BUILDING AUTOMATION AND CONTROL FOR THE IMPROVEMENT OF ENERGY EFFICIENCY AND CLIMATE COMFORT OF OFFICE BUILDINGS 1

Gábor KŐVÁRI, 2István KISTELEGDI Jr

Department of Energydesign, Pollack Mihály Faculty of Engineering and Information Technology, University of Pécs, Boszorkány u. 2, H-7624 Pécs, Hungary e-mail: 1 [email protected], [email protected]

Received 1 January 2013; accepted 11 September 2014

Abstract: The object of the examination is a typical office building of the 1990s, owned by a multinational company -Siemens- dedicated to energy awareness. The building also meets the energy efficiency category ‘A’ under the 7/2006 TNM Hungarian regulations concerning the energy performance definition of buildings. However, demand has emerged to implement additional changes to reduce energy usage whilst keeping the current climate comfort or even improving it. International experience forecasts around 30% energy saving potential due to optimization of the building automation and energy management system, and thus the interaction and collaboration between the building geometry, structures and services systems. The project has been built in the IDA ICE complex building energy simulation program. Running a one-year dynamic simulation will provide data that can be compared with the measured data of the actual building, so the model can be adjusted and validated to real data. After the calibration it is now possible to test the ideas under safe conditions, in a virtual surrounding. Once a particular vision of the model is proven to work effectively, it is possible to apply this to the real building control management as well. Keywords: Office buildings, Building renovation, Energy-efficiency, Energy optimization, Energy management, Building automation systems, Monitoring validated dynamic building simulations

1. Budapest 2013, a typical office building The subject of the research is to find answer(s) to the question on how can an existing (office) building’s overall energy efficiency get improved, whilst keeping the evolved climate comfort of it, or even improving it, if necessary. In the first instance, it HU ISSN 1788–1994 © 2015 Akadémiai Kiadó, Budapest

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needs to be determined what kind of offices dominates the office building stock in Budapest nowadays. 1.1. Office buildings, new or existing It shall not be forgotten that the EU directive EPBD/2010/31/EU [1] of the European Parliament - which prescribes that after 2020 all newly designed and constructed buildings in the member states must meet the requirements of a nearly zero-energy building - also concerns to the existing buildings, building units and building elements that are subject to major renovation [1]. Furthermore, the execution of the Energy Roadmap 2050 by the European Commission [2] - that aims to reduce the greenhouse gas emissions to 80-95% below 1990 levels by 2050 - cannot perform without refurbishing the existing building stock. Usually, the different terms of green design, sustainable architecture or energy efficiency correspond to new buildings only. Existing buildings tend to be easily forgotten in these topics. In average, 98% of the world’s building stock consists of existing buildings. In Hungary official records show that in 2010 there were 4 302 827 flats, while in 2013 between January and September 2680 flats [3] have been built, which is less than 0.1%. Taking a look at the office building market, similar figures will be found. The existing office building area in 2012 were 3 158 889m2 and 36 000 m2 were built. That is 1.1%. In 2013 no new office building expected to be completed as shown in Fig. 1.

Fig. 1. Completed office area in Budapest [4]

1.2. Office buildings, class B, A and A+ It is natural to take a quick look of the distribution of offices by overall quality category. However this measure has low impact on energy efficiency, it would give as a good view on climate comfort and tendencies in office market. As it can be seen in Fig. 2 the majority of the offices belong to class A. This category’s specification can be

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found in Table I [5]. From the point of interest the most important fact is that these buildings are disposed with Heating, Ventilation, Air Conditioning (HVAC) system and control, building management system, dual power supply, raised floors and energy efficiency class A certification. This is the most common quality level among the developers, while class B is not a goal to build any more. Since 2007 -top quality- A+ offices are more frequently developed. It should be noted that according to international office building developers the average class A office in Budapest cannot reach the average international category A.

Fig. 2. Office class in Budapest [6]

1.3. Office buildings, by state Talking about office buildings, the third attribution, which should be examined is the state of the buildings. Beyond dividing them into new and existing ones, it is obligatory to investigate more explicitly the available buildings, in order to obtain precise picture about the quality of them. In this way e 3 distinct categories can be found. In the first category there are the brand new buildings, typically 1 to 3 years old. They are usually built of quality materials, have good building management control and designed very well energetically. In the second one there are the old buildings, built around or before the 60’s. Their layout cannot be modernized economically, furthermore they are poorly insulated. In short, they are not worth to refurbish. In the third category buildings have been built in the 70’s through the 90’s with good or easily modifiable layout. Extra insulation and up-to-date engineering can be applied. These buildings have good


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potential to lower their energy consumption. The aims of this research is to focusing on these particular buildings (Fig. 3). Table I Compulsory characteristics of a class A office building [5] No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Characteristic First-class design of a newly constructed building Excellent location Easy access to the building Attractiveness to the most creditworthy and prestigious tenants on the market High rent levels Professional property management Underground parking lot providing enough parking space for the building Use of high-quality building materials Floor to ceiling height not less than 2,70 m Flexibility of internal design - ‘open space type’ Underfloor cabling system (raised floors) and suspended ceilings 24-hours security and access control High-speed lifts with waiting time max up to 30 sec. At least 2 lifts with a capacity of at least for 6 people HVAC system to provide heating, cooling and humidity control of the air and control of microclimate in the office according to the EU HVAC standards. Dual power supply with automatic switch Room depth 18-20 m between windows Common areas not more than 12 percent of TBA (total brut area) Building Management System Luxury meeting rooms and a large impressive lobby Food and rest areas for staff /restaurant, café, fitness/ for the buildings designed for more than 250 people Modern window panes, high-quality window frames, sun-protection glass Energy efficiency class A

Fig. 3. MOMentum office building Budapest [7]



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2. Siemens office building Nr. 8 Siemens, this huge multinational company, dedicated to energy awareness, gave us access to one of its office building management to implement additional changes in order to reduce the building’s energy usage, whilst keeping the current climate comfort or even improving it. This joint research program between the University of Pécs and the Siemens cPlc is a great possibility to study and apply the ideas of complex simulations on a real, functioning building. In this way the conceptions could be certified not only theoretically, but also in real-life. The building is located in Budapest, on the south side of boulevard Hungária, close to Városliget, in district XIV, northeast of the city center (Fig. 4). In this site there are 10 buildings - mainly offices - all belonging to Siemens. The original building was built in 1974 and refurbished in 2010-11. The overall building area is 9668 m2, the volume of the building is 32 433 m3, consist of a basement, ground floor and 5 stories. For approximately 380 office-worker, the average working hours are between 9 am to 6 pm.

Fig. 4. Siemens building Nr. 8.

In 2010-11 the refurbishment was not entirely complete. Although windows were changed everywhere, new heating system were installed, the whole building got a 15 cm thick Styrofoam thermal insulation, some floors remained in mixed state. Fan coils and building management control were applied only on the 3rd and 4th floor. For some reason on ground floor, 1st, 2nd and 5th floor radiators were kept. These floors’ heating systems are connected to the building monitoring system, but controlled manually in the rooms. Solar panels were installed on the roof to help providing domestic hot water. 8 pieces of outdated gas boilers - combined performance of almost 1MW - were replaced by 5 pieces 100 kW performance ones. On the corridors smart lighting system is Pollack Periodica 10, 2015, 1

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installed, which can adjust the lighting according to the number of tenants present, date and time and outdoor conditions. Window external shading is controlled manually (Fig. 5).

Fig. 5. Siemens building Nr. 8

Before refurbishment, the building’s primary energy consumption was 132.90 kWh/m2a, total heat loss (winter) was 537.76 kW. After refurbishment, the building’s primary energy consumption could be reduced by 51%, (75.90 kWh/m2a), the total heat loss was halved (264.13 kW), and the energetic category jumped from D to A. In addition to this current state, this research hypothesis predicts even more efficiency improvement. Due to the simulation supported optimization of the building automation, hided energy potentials in the building structures, services systems and operation schedules can be detected, new innovative operation concepts developed, and in this way the overall system can be still refined, the energy saving increased.

3. The energy design method The generalized process of energy design can be applied to both new construction and retrofitting existing buildings. One of the huge differences between these two is that during the predesign phase of remodels and retrofits, the existing building structure needs to be studied in detail, and will introduce a whole set of design constraints. The same design strategies will apply to both, but designers will not have as much latitude to reshape existing buildings. When working on an existing building, it is essential to understand the energy use of the building, its thermal performance, existing equipment, control schedules, occupancy patterns, lighting and other systems. In most cases it is difficult to get detailed information on constructions and other things that cannot be readily observed. The existing building’s modeling process consists of different steps. Firstly, the project shall be built in the IDA ICE complex dynamic building energy simulation program, setting up all the parameters that can influence the energy and climate comfort Pollack Periodica 10, 2015, 1


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(building structures, equipment, HVAC, and users). Running one-year simulations will provide results that can be compared with the measured data of the actual building, so the model can be re-calibrated and adjusted to real data. After the calibration it will be already possible to test the new concepts for the improvement of the energy balance under safe conditions, in virtual surroundings. In this way prevention is ensured, from creating a possibly worse situation of climate comfort or energy efficiency by experimenting with the control of the real building. Once a particular vision among the operation concepts of the model is proven to work effectively, it shall be possible to apply this to real building control as well. Taking a look in Fig. 6 and Fig. 7 the detailed flowchart of the energy design process can be seen. The chart and the designing process itself divided into three parts.

Fig. 6. Energy design flowchart


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Fig. 7. Energy design flowchart

In part one all the parameters related to the building’s architecture: geographical location and orientation, building layout and geometry, structures are defined. During creating an energy model of a building, abstraction from the real architectural geometry and space-structure is needed. It should be kept in mind that the model is made up of zones, building body and not rooms and spaces. Complex simulations can take up more days to run, so in order to get results in reasonable time simplification of the architectural layout is needed. However this simplified model must include all required building physics features for adequate building climate and energy performance simulation results. Merging neighboring, secondary rooms, for example toilets, storages and staircases, where no permanent tenant activity exists, and that are not primary comfort zone, can reduce the calculation time largely. The software facing difficulties handling non-perpendicular walls, so avoiding these is necessary by transforming the layout into an approximate state, while keeping the original building physics related



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dimensions. When the architectural geometry, the frame of building is done, the structural layers of the boundary walls and slabs needed to be set up by creating and assigning the layered constructions to the appropriate outer and inner walls and slabs. There are three more element types, which have to be installed to get punctual results: openings (doors), transparent structures (windows), as well as sun shading and protection. It is always advisable following one modeling phase to generate the mathematical model of the project, so the software can highlight the errors made during modeling. In the second phase the building engineering and tenants’ activity patterns should be examined. First, the setup of the building services system with all its parameters (Air Handling Units (AHU), plant and control) need to be done. Decentralized building services system, heat delivery system, AHU, air volume and flow rate, etc. should be defined in each and every zone. Configuring the user profile is also important, since for e.g. cooling energy could be saved by ignoring overheated areas, where no tenants present at the moment of the problematic time interval. The third phase is the goal of the research work: to test the energy saving strategies via simulations.

4. Strategy to define the impact of the building automation optimization on the energy efficiency in building Nr. 8 Even tough, after refurbishment the building’s energy performance was developed (primary energy consumption and total heat loss halved), professionals at Siemens had the notion that the results should be even better. International studies confirm this conjecture, according to which 30% more energy savings can be achieved by optimization of the buildings management system (automation), and thus the interactive collaboration-operation of the structures and the building services system. The Department for Energydesign at the University of Pécs was involved in research to find solutions to reach this targeted extra saving. In most of the cases during working with existing buildings, it is difficult to find appropriate plans of the engineering, number of tenants, and list of equipment used in each room. This is also true in this case. Engineering plans are very limited. Only the measuring and reckoning of the utility companies could be relied on. A personal survey of the building is needed to get a trustworthy picture of people and equipment (computers, laptops, copy machines, desk lamps, etc.) in the building. After examining the current situation of the building both positive and negative characteristics were found. It is fortunate that the building equipped with building monitoring and control system, but the control does not extend to all stories and monitoring is not supervised. The refurbishment was not entirely consistent, mixed heat transfer system (centrally controlled fan coils on the 3rd and 4th floor, while manually controlled radiators on ground floor, 1st, 2nd and 5th floor). Although solar shading devices were installed on the facades, but they are not connected to the building management and control system tenants can control them randomly -, no ‘follow the sun’ module was set up. There are window opening sensors on 3rd and 4th floor, but not on the rest. A solar collector system - installed on the flat roof- helps reducing domestic hot water energy usage. The Pollack Periodica 10, 2015, 1

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regulation of the corridors’ artificial lighting is not satisfactory, often too ‘slow’ to react. Beyond the deficiencies the biggest advantage of the building shall not be forgotten: the monitoring and control system. Without that, it would be almost impossible to examine, check, calibrate and improve the energy model of the building. The building management control system makes possible to apply the recommended changes and adjustments, which will be already proven to work flawlessly in the theoretical model under safe conditions. Re-regulating the real building control allows us to compare and validate the measured and theoretical data, confirming which of the concepts were efficient or more adjustments are necessary. The current - and most important - step on the road of remodeling an existing building’s energy usage is the establishment of a predefined condition. Even if flaws in the system can be seen clearly, the simulation’s end-result shall not be correct and cannot be corrected, if the initial state of a building and the simulation model’s adjustments are different. In this kind of cases simulation results will be distorted from the real physical parameters of a theoretical or real building. For this reason it is obligatory to preset identical values both in the building systems as well as the simulation model in order to preserve a maximum on simulation precision. At the moment the dynamic building energy simulation model of the Siemens office building is in progress (Fig. 8 and Fig. 9).

Fig. 8. Multiclimate zone simulation model of the Siemens office building

After finishing to set up the whole energetic model, a whole year, complex simulation can be run. Results must be compared with the data available from the original building. If a significant difference shall appear, the model should adjusted until original and calculated data are consonant.



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Fig. 9. 3rd story of the Siemens office building’s simulation model

The next step is to test all the theories one by one: central plant operation strategies, decentralized Individual Room Controlling (IRC) operation strategies, thermal mass structures strategies, artificial lighting strategies, night cooling strategies and ventilation strategies. Every simulation would result data, that can be compared and the best performance strategy can be selected to put into practice.

5. Conclusion According to the Intergovernmental Panel on Climate Change, ‘over the whole building stock, the largest portion of carbon savings by 2030 is in retrofitting existing buildings and replacing energy using equipment’ [8] and energy savings for 50-75% can be achieved in commercial buildings that make smart use of energy efficiency measures. The techniques to create a realistic and accurate model of a building’s energy profile already exist. Examining the behavior of this profile makes it possible to locate the weaknesses. By eliminating these faults, elaborating new innovative building management concepts and fine-tuning the building’s control system and equipment, maximized building energy efficiency can be greatly increased by simultaneous improvement of the real measurement validated building simulation technique. Looking at the vast proportion of existing (office) buildings, it is important to understand how crucial is the improved remodeling the energy usage of the buildings already owned.

Acknowledgements This work is part of the collaboration research project between the Pollack Mihály Faculty of Engineering and Information Technology, University of Pécs and the Siemens cPlc. Pollack Periodica 10, 2015, 1

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